Authors: H.B. Whittington and W.R. Evitt II
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Sixteen species of trilobites, 15 new, distributed equally among 8 genera, 3 new, are described. The material is from Middle Ordovician limestones of Virginia, and the undistorted exoskeletons are preserved as a thin layer (or layers) of granular quartz. The most minute morphological features are beautifully preserved. The exoskeletal parts are dissociated and range in size from less than 1 mm. to 2-3 cms. The holaspid has been reconstructed, and the development of each species is described; the protaspid of one genus is known. Stereographic illustrations aid in revealing morphological form and detail. Dimeropyge Opik, Mesolaphraspis n. gen., and Chomatopyge n. gen. are referred to the family Dimeropygidae. All these trilobites are small, characterized by sagittal depressions in the cephalon and/or the pygidium, and include forms with a rostrum, and forms without connective or median sutures. Onchaspis Raymond is synonymous with Ceratocephala Warder, and the two new species are the oldest known of this long-ranging widespread genus. Of the Cheiruridae, Ceraurinella Cooper and Sphaerexochus Beyrich are represented, and the new subfamily Acanthoparyphinae is erected to include Acanthoparypha n. gen. and Holia Bradley. Acanthoparypha is closely related to Nieszkowskia Schmidt, and the complete exoskeleton of Holia is described for the first time…
Published: 12/08/1953
Pages: 137
Product Category: Memoirs